The present invention relates to packaging machines for containers such as cartons for containing milk, and more particularly to packaging machines including a bottom breaker.
Packaging machines of the type mentioned include those already known which comprise, as disclosed in JP-Y No. 6-46669, a movable body having mandrels and intermittently drivable so as to stop each of the mandrels at a process station while carrying containers as fitted around the respective mandrels with a bottom forming portion of each container projecting outward from the mandrel, the bottom forming portion having first to fourth bottom panels facing toward the upstream side with respect to the direction of movement of the mandrel, rightward, downstream side with respect to the direction of movement of the mandrel and leftward, respectively, and a bottom breaker for forming folds in a bottom forming end portion of the container fitted around the mandrel as halted at the process station so as to render the end portion foldable flat, the bottom breaker having first folding means and second folding means, the first folding means being operable to fold the second and fourth bottom panels in two into triangles first, the second folding means being operable to fold first and third bottom panels subsequent to the second and fourth bottom panels, the second folding means having a folding member movable axially of the mandrel as halted at the process station, the folding member being movable into pressing contact with the first bottom panel and the third bottom panel for folding.
With the packaging machine described, the folding member comes into rubbing contact with the first bottom panel and the third bottom panel for folding, consequently marring these bottom panels to result in an impaired commercial value, producing polyethylene fragments as removed from the container surface or releasing paper particles, hence insanitation. Especially when the container is moved with the mandrel after folding, the first and second bottom panels are strongly rubbed against the folding member.
Furthermore, the folding member is reciprocatingly moved linearly in addition to the frictional contact with the bottom panels, so that it has been difficult to operate the machine at a higher speed.
The folding angle of the first and third bottom panels is dependent on the shape of the portion of the folding member to be brought into contact with these panels. It is therefore not easy to adjust the folding angle even if an attempt is made to increase the folding angle of the first and third bottom panels. Different materials used for containers require the adjustment of the folding angle.
Further because the first and third bottom panels are pressed in the same direction at the same time by the folding member, the outer edge portion of the first bottom panel is not always smoothly inserted by folding between the outer edge portion of the third bottom panel and the triangular portions of the second and fourth bottom panels.
An object of the present invention is to overcome the foregoing problems and provide a packaging machine which is unlikely to impair the commercial value of the product and which is capable of folding the bottom forming portions of containers to the desired finished shape and adapted for a high-speed operation.
The present invention provides a packaging machine which comprises a movable body having mandrels and intermittently drivable so as to stop each of the mandrels at a process station while carrying containers as fitted around the respective mandrels with a bottom forming portion of each container projecting outward from the mandrel, the bottom forming portion having first to fourth bottom panels facing toward the upstream side with respect to the direction of movement of the mandrel, rightward, downstream side with respect to the direction of movement of the mandrel and leftward, respectively, and a bottom breaker for forming folds in a bottom forming end portion of the container fitted around the mandrel as halted at the process station so as to render the end portion foldable flat, the bottom breaker having first folding means and second folding means, the first folding means being operable to fold the second and fourth bottom panels in two into triangles first, the second folding means being operable to fold first and third bottom panels subsequent to the second and fourth bottom panels. The packaging machine is characterized in that the second folding means has an upstream arm and a downstream arm each pivotally movable toward and away from the other about an axis extending transversely of the direction of movement of the mandrel, the upstream arm being movable into pressing contact with the first bottom panel for folding, the downstream arm being movable into pressing contact with the third bottom panel for folding, the downstream arm being provided at a portion thereof to be contacted with the third bottom panel with a pressure roller having an axis of rotation extending transversely of the direction of movement of the mandrel.
With the packaging machine of the present invention, the second folding means has an upstream arm and a downstream arm each pivotally movable toward and away from the other about an axis extending transversely of the direction of movement of the mandrel. For folding, the upstream arm is moved into pressing contact with the first bottom panel, and the downstream arm is moved into pressing contact with the third bottom panel. The downstream arm is provided, at a portion thereof to be contacted with the third bottom panel, with a pressure roller having an axis of rotation extending transversely of the direction of movement of the mandrel. The pressure roller is therefore unlikely to mar the third bottom panel and to impair the commercial value of the container. Furthermore, the machine produces or releases none of extraneous substances such as polyethylene fragments.
Since the upstream arm and the downstream arm act on the first and third bottom panels, respectively, from a direction approximately orthogonal thereto, these panels can be folded smoothly without forcible folding.
When the upstream arm is provided at a portion thereof to be contacted with the first bottom panel with a pressure roller having an axis of rotation extending transversely of the direction of movement of the mandrel, the first bottom panel, in addition to the third bottom panel, is also unlikely to become marred and is effectively prevented from releasing extraneous matter.
When the upstream arm and the downstream arm are mounted respectively on a pair of pivots extending in parallel to each other and adjustable in the angle of pivotal movement, the folding angle of the first and third bottom panels can be adjusted easily by adjusting the ranges of pivotal movement of these arms.
If the upstream arm is made longer than the downstream arm, the first bottom panel and the third bottom panel can be folded at different speeds. When the first bottom panel is made foldable more rapidly than the third bottom panel, these first and third bottom panels can be folded to the desired shape reliably.
A folding rail is further disposed so as to guide the bottom forming portion of the container as fitted around the mandrel moving from the process station while folding the bottom forming portion flat by contact therewith, the mandrel being movable with the pressure roller of the downstream arm in contact with the third bottom panel, and the third bottom panel of the container as fitted around the mandrel being moved is brought into contact with the folding rail while the third bottom panel is held in contact with the pressure roller. The folding rail further folds the bottom forming portion more reliably without the likelihood of unfolding from the state as folded by the upstream and downstream arms.
When the first folding means and the second folding means are driven individually by respective actuators, the timing of folding by these folding means can be determined as desired.
Accordingly, without the likelihood of impairing the commercial value of the product, the bottom forming portions of containers can be folded to the desired finished shape by the machine of the invention which is made operable at a higher speed.